AU731723B3 - A retractable needle assembly for a catheter and which uses vacuum to retract the needle - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A PETTY PATENT Name of Applicant: Actual Inventor: Address for Service: Invention Title: OCCUPATIONAL MEDICAL INNOVATIONS LTD Bruce Leigh KIEHNE CULLEN CO., Patent Trade Mark Attorneys, 239 George Street, Brisbane, QId. 4000, Australia.

A RETRACTABLE NEEDLE ASSEMBLY FOR A CATHETER AND WHICH USES VACUUM TO RETRACT THE NEEDLE The following statement is a full description of this invention including the best method of performing it known to A RETRACTABLE NEEDLE ASSEMBLY FOR A CATHETER AND WHICH USES VACUUM TO RETRACT THE NEEDLE FIELD OF THE INVENTION This invention relates to a retractable needle assembly which can be used with a catheter, with the needle acting as the puncture needle, and where the needle can be retracted after use using vacuum.

BACKGROUND ART A catheter can comprise any of various tubular medical devices designed for insertion into veins or body cavities so as to permit injection or withdrawal of fluids or substances or to maintain the openness of a passageway. Catheters are widely used in hospitals for withdrawal of blood from a patients body. In practice, the catheter comprises a puncture needle which is typically a conventional injection needle. About the puncture needle is a cannula. The cannula comprises a cannula needle through which the puncture needle passes. The cannula needle does not have a sharp tip (as it does not itself puncture the body). The cannula needle is fitted to a plastic cannula base.

In use, the puncture needle penetrates into the persons body and passes into the persons vein. The cannula needle is then pushed forwardly to also enter into the persons vein. The puncture needle can then be retracted. A tube or other type of container can then be attached to the cannula base to collect the blood.

As the puncture needle is retracted entirely out of the cannula needle, it presents a sharps hazard, and also a bio-hazard due to contamination of the needle with body fluids. For this reason, various attempts have been made to reduce the sharps hazard and also the biohazard.

Various known arrangements use tip protection to reduce the hazard. The tip protection comprises some form of cover which is placed over the sharp tip of the puncture needle after the needle has been used.

Attachment of these types of tip protectors can in itself create a hazard. It is also known to provide a shoot back needle for a catheter where the puncture needle is biased by a helical spring to shoot back into some form of holding body after the cannula needle has been inserted.

It appears that attempts have been made to use vacuum to shoot back the puncture needle after use. However, in these arrangements, the needle is attached to some form of base member which is under permanent vacuum. That is, the puncture needle assembly is purchased with the assembly already under vacuum. This raises a host of potential difficulties. For instance, it is envisaged that air may slowly leak into the holding body over time to gradually decreased the vacuum. This could typically occur if the puncture needle assembly is stored for a period of time before use. If vacuum is lost, this is not at all evident by a user until it becomes obvious that the needle will not shoot back properly and this can then create a sharps hazard or a bio-hazard. Another disadvantage is that transportation, handling and storage of such permanently depressurised assemblies may create safety hazards. For instance, an assembly could conceivably implode if handled roughly or accidentally knocked, dropped and the like.

OBJECT OF THE INVENTION The present invention is directed to a retractable needle assembly which uses a vacuum to shoot back (or suck back) a used puncture needle but where the vacuum is created immediately prior to use. Therefore, during manufacture, transportation and storage, the assembly is not under vacuum.

It is an object of the invention to provide a retractable needle assembly which may overcome the abovementioned disadvantages or provide the public with useful or commercial choice.

In a broad form, the invention resides in a retractable needle assembly where the needle is retracted by a vacuum, and where the vacuum is created immediately prior to use of the needle assembly.

In a more particular form, the invention resides in a retractable needle assembly for a catheter and which uses a vacuum to retract the needle, the assembly comprising: a. a tubular barrel which is closed at a rear end and open at a front end, b. a removable cap which is slidable in the barrel from a retracted position where the cap is substantially within the barrel to an extended position where the cap can be removed, c. a collar which is slidable within the barrel, d. a plunger in the barrel and which is moveable along the barrel between a retracted position where the plunger is adjacent the closed rear end of the barrel, and a vacuum creating extended position where the plunger is at a position spaced from the rear end, and a vacuum is created between the plunger and the rear end which biases the plunger back towards the retracted position, e. a puncture needle operatively connected to the plunger, f. a cannula having cannula needle which extends over the needle, and a cannula base to which cannula needle is attached, g. engagement means to releasably connect the cap to the collar, and, h. trigger means which operatively connects the plunger to the collar, the trigger means extending from the barrel when the cap is in the extended position, and in this position able to be operated to release the plunger from the collar causing the plunger to be biased by the vacuum back to its retracted position which causes the attached puncture needle to be retracted into the barrel.

While the retractable needle assembly will be described with reference to its use with a catheter, it is envisaged that the invention need not be limited to only this use.

The retractable needle assembly may have a tubular barrel. The tubular barrel is closed at a rear end and open at a front end. Suitably, the tubular barrel is in the form of an elongate hollow cylinder having one open end and one closed end. The barrel may be formed from any suitable material and it is typical for the barrel to be formed from plastics material. However, it is envisaged that the barrel may also be formed from glass. Preferably, the barrel is formed of clear material. The barrel may have various lengths and diameters depending, inter alia, on the length of the puncture needle. It is envisaged that the barrel will have a length of between 50-150 mm, and a diameter of between 5-30 mm. This can of course vary to suit. The barrel should have a wall thickness or wall strength suitable to accommodate the temporary vacuum without undue deformation of the wall. This will of course depend on the type of material used in the manufacture of the barrel.

The barrel may have engagement means to engage with the cap to hold the cap in its retracted position. This can prevent the cap from inadvertently falling out of the barrel, for instance, if the assembly is held upside-down.

The engagement means may be in the form of an inwardly extending projection which may be adjacent the open front end of the barrel. The inwardly extending projection may comprise a collar retaining ring.

The barrel may be provided with grip enhancing means. The grip enhancing means may comprise one or more projections extending outwardly from the outer wall of the barrel. The projections may be in the form of annular rings or ribs which are typically formed integrally with the barrel. The projections may have land portions to prevent the barrel from rolling on a flat or inclined surface.

The assembly may comprise a removable cap. The cap may function to cover the puncture needle prior to use of the assembly. The cap may comprise a substantially elongate tube which can have a lower open end.

The elongate tube may be configured to allow it to slide within the barrel between a retracted position where the cap is substantially within the barrel, to an extended position where the cap can be removed from the barrel to expose the needle. The cap may have an inner end and an outer end, with the inner end being inserted in the barrel, and the outer end extending from the barrel even when the cap is in its retracted position. The outer end may be provided with grip enhancing profiles such as annular ribs or rings to allow a person to pull the cap out of the barrel. The cap may be formed from any suitable material and is typically formed from plastics. It is preferred that the cap does not extend entirely through the barrel but terminates at a position spaced from the rear end of the barrel. The outer end may extend sufficiently to ensure that the puncture needle is shielded at all times before the assembly is used.

The tubular cap may comprise an engagement means which may be adjacent the inner end of the cap. The engagement means may function to releasably engage the cap to the collar. The engagement means may be in the form of a pair of barbs which may be diametrically opposed from each other. The inner end region of the cap may comprise a pair of leg members with each leg member containing a said barb. The leg members may be provided to allow the cap to be released from the collar by pressing the leg members together once the cap has been sufficiently withdrawn from the tubular body. This will be described in greater detail below.

The assembly may include a collar which is slideable within the barrel. The collar may comprise a cylindrical tubular member which has an internal passageway. The collar may be formed from any suitable material such as plastics. The collar may have a forward portion provided with at least one side wall recess through which the engagement means may engage to releasably engage the cap to the collar. The collar may be configured to support the trigger means. The collar may support the trigger means in a tensioned manner which means that the trigger means is tensioned or biased to a cocked position. This may be achieved using a wedge block which may form part of the collar.

The assembly may include a plunger. The plunger is positioned in the barrel and is moveable along the barrel. The plunger typically has a plunger head and a plunger body. The plunger head may be provided with a rubber or other type of seal in a manner which is similar to plungers used with conventional syringes. The plunger head may be positioned at a lowermost portion of the barrel, that is the portion closest to the closed rear end of the barrel. The plunger body may be elongate and substantially cylindrical. The plunger body may be provided with an alignment ring extending about the body to facilitate smooth movement of the plunger along the barrel. A forward part of the plunger head may have means to connect it to a puncture needle.

The plunger body is preferably formed of clear material and is preferably substantially hollow to allow a flash of blood to be seen in the plunger which signifies successful penetration of the needle into the persons vein. An air permeable (but blood impermeable) partition is preferably provided in the hollow body and spaced from one end of the body which may act as a vent.

A forward part of the plunger body may be configured to allow it to be releasably connected to the trigger means. In one form, the forward part of the plunger body may have at least one recess or cutout for this purpose.

A puncture needle may be provided to puncture the persons body. A conventional puncture needle may be used. The puncture needle is operatively connected to the plunger, and is preferred that the puncture needle communicates with the hollow part of the plunger body to allow blood to flow into this part.

A cannula may be provided. The cannula may be of conventional manufacture and may comprise a cannula needle and a cannula base to which the cannula needle is attached. The cannula base may be provided with a small projection to facilitate forward pushing of the cannula into the persons vein. The cannula base is typically hollow and fitted over a forward portion of the plunger body. The cannula base may also be releasably engageable with the collar.

A trigger means may be provided which operatively connects the plunger to the collar. The trigger means can function to hold these two parts together, but upon operation of the trigger means, the two parts are released from each other. The trigger means is preferably supported by the collar and stays on the collar throughout use. The trigger means may comprise a U shaped member having a pair of leg members, the leg members having thickened portions which can engage with the plunger to holdtheplunger to the collar.

Upon operation of the trigger means, the leg members may be forced apart which can release the plunger from the collar. The wedge block which may be provided on the collar can function to assist in this action.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described with reference to the following drawings in which: Figure 1 Figure 2 Is a part section view of a needle assembly prior to use.

Is a partially cut away view of the assembly of figure 1.

Figure 3 Illustrates a partially cut away view of the needle assembly at the start of the arming action that is, creation of the vacuum).

Figure 4 Figure 5 Illustrates the assembly of figure 3 in a cocked position, where vacuum has been created, but where the plunger is prevented from moving back by the trigger means being cocked.

Illustrates removal of the cap from the barrel.

Figure 6 Illustrates initial forward movement of the cannula.

Figure 7 Illustrates operation of the trigger means to cause the puncture needle to shoot back into the barrel.

Figure 8 Illustrates the used puncture needle in the fully retracted position.

Figure 9 Illustrates a partially cut away view of the trigger means.

BEST MODE Referring to the drawings and initially to figures 1 and 2 there is illustrated a needle assembly for use with a catheter. The needle assembly comprises the following main parts: An outer tubular barrel An inner slideable cap 11 A collar 12 A plunger 13 A puncture needle 14 A cannula having a cannula needle 15 and a cannula base 16 A trigger means 17 lO Referring in greater detail to each of these components, barrel 10 comprises a cylindrical body having a rear closed end 18 and an open front end 19. The barrel has a length of between 5-20 cm and a diameter of between 5-20 mm.

The barrel is formed from plastics material. Adjacent open end 19 is a single inwardly extending annular collar retaining ring 20 which is formed integrally with the barrel. On the outside wall of barrel 10 are three spaced apart extending ribs 21-23 which form grip enhancing profiles on the barrel which may be necessary if the needle assembly is wet and slippery with body fluids and the like.

Slideable inside barrel 10 is a cap 11. Cap 11 functions to cover the puncture needle 14 prior to use of the assembly, and also assists in cocking the assembly to create the required vacuum immediately prior to use. Cap 11 is removable from the barrel by which is meant that it can be slid entirely out of the barrel to fully expose the puncture needle 14. Cap 11 is tubular and has an outer end 24 which extends proud of the front of barrel 10, for instance by a distance of from 5-25mm, even when the cap is fully inserted in the barrel.

The outer end is provided with an array of spaced apart ribs 25 which form grip enhancing profiles on the cap which may be necessary to allow the cap to be withdrawn especially if it is wet and slippery with body fluids and the like. Cap 11 has a small outer annular recess 26 which engages with retaining ring 20 on barrel 10 to releasably lock cap 11 to barrel 10 when the cap is in the fully inserted position as illustrated in figure 1. This arrangement lightly locks cap 11 to barrel 12 to prevent it from being inadvertently removed from the barrel. However, by gripping cap 10 about ribs 25, the cap can be pulled out of barrel The inner end of cap 10 includes a pair of leg members 27, 28 (best illustrated in figure 2) which are formed integrally with the cap. The leg members 27, 28 are partially curved to conform with the inside curvature of barrel 10. Each leg member terminates with an outwardly extending barb, figure 2 illustrating barb 29 on leg member 27. The barbs releasably engage with collar 12 as will be described in greater detail below. Cap 10 has a lo length such that it engages with collar 12 but does not extend entirely along barrel Collar 12 is best illustrated in figure 2 and comprises a generally hollow body through which a portion of the plunger can pass. A forward portion of collar 12 is provided with two diametrically opposed cutouts 30, 31 (only one cutout being illustrated in figure These cutouts function to receive a respective barb 29 on each leg member 27, 28 of cap 11. In this manner cap is attached to collar 12 by the barbs 29 extending into cutouts 30, 31.

However, cap 11 can be released from collar 12 by squeezing leg members 27, 28 towards each other which cause barbs 29 to move out of the respective cutouts 30, 31. This occurs once cap 11 has been sufficiently withdrawn from barrel 10 to free the leg members from the barrel and to allow the leg members to be squeezed towards each other.

A plunger 13 is provided. The function of plunger is to hold the puncture needle, to provide a flash chamber to view blood, and also to provide the vacuum as the plunger is withdrawn through barrel 10. Plunger 13 has a plunger head 32 and a plunger body 33. Plunger head 32 is typically more or less of conventional manufacture and contains a rubber bung 34 which is in a sliding sealing engagement with the inner wall of barrel 10. The plunger is fitted into barrel 10 such that plunger head 32 sits against or is closely spaced from rear end 18 of barrel 10. Plunger body 33 is elongate and substantially cylindrical and extends rearwardly from plunger head 32. A forward part 35 of plunger body 33 has a narrow passageway through which the puncture needle 14 can pass. In this manner, puncture needle 14 is attached to plunger body 33. Plunger body 33 has an internal chamber 36 best illustrated in figure 1. Chamber 36 has one end wall 37 which is defined by a part of rubber bung 34, and an opposed end wall 38 which communicates with puncture needle 14. Blood or other fluid passing through puncture needle 14 can therefore pass into chamber 36. The plunger body is formed of a clear material such that the contents of chamber 36 can be viewed through the assembly. Chamber 36 is defined by a wall which has an annular step 39 against a which is seated a paper flash pad 40. Flash pad 40 is known and comprises an air permeable, but blood impermeable material. As blood enters into chamber 36, it forces the air within the chamber to pass through pad 40, and this air can vent through vent holes 41, which are formed through the wall of chamber 36.

The forward part 35 of plunger body 33 passes through collar 12 and is not held by the collar. That is, plunger body and collar are free to move apart.

These two parts are releasably held together by trigger means 17. Trigger means 17 is most clearly illustrated in figure 9. Referring to figure 9, trigger means 17 is formed from plastics material and is substantially U shaped and has a pair of leg members 42, 43 and a bridging connecting member 44. The leg members 42, 43 have lower thickened portions 45, 46 which diverge away from each other. Collar 12 has an integrally formed wedge block 47 which is positioned such that leg members 42, 43 extended to each side of wedge block 47. Wedge block 47 has convergent side walls which complement the divergent thickened portions 45, 46 of each leg member. Therefore, if trigger means 17 is pushed more towards wedge block 47 this will have the effect of pushing apart leg members 42, 43. A dome shaped member 59 is provided as a structural and alignment member to provide strength along the perforated section of the collar, and providing a means for alignment and location of the trigger means by way of a corresponding recess Plunger body 33 is formed with a pair of opposed cutouts 50, 51 these being best illustrated in figure 7. When plunger body 33 is initially pushed through collar 12, the thickened portions 45, 46 of each leg member 42, 43 pass into cutouts 50, 51 which has the effect of locking trigger means 17 to plunger 13.

Referring to figure 2, collar 12 has a rear portion containing a pair of spaced apart extending ribs 52, 53 which locate the leg members 42, 43 of trigger means 17. In this manner, trigger means 17 is attached to collar 17 and cannot be readily detached from the collar.

When assembled, plunger 17 has its plunger body 33 extending partially through the internal bore of collar 12. Trigger means 17 is then attached to lock the plunger 17 to collar 12. This is achieved by the leg members 42, 43 of trigger means 17 being trapped between ribs 52, 53 (to lock the trigger means to the collar), and the thickened portions 45, 46 of each leg member 42, 43 passing into the respective cutouts 50,51 on the plunger body 33. As well, trigger means 17 has each leg member 42, 43 extending partially along the tapered wedge block 47. This has the effect of biasing trigger means in the direction of arrow 54 illustrated in figure 9. That is, the trigger means 17 is biased or tensioned to want to push away from the wedge block 47, due to leg members 42, 43 being slightly prised apart as they pass over the initial part of wedge block 47. This slight prising apart of the leg members is sufficient to provide the bias, but insufficient to release the thickened portions from engagement in the cutouts 50,51.

A cannula base 16 is fitted over forward portion 35 of plunger body 33.

Cannula base 16 has an outwardly extending annular rib 56 which can engage with collar 12. A cannula needle 15 extends about puncture needle 14 as is conventional. Cannula base 16 fits over the forward part of plunger body 35 also called the plunger tip), to secure it to the plunger body.

In use, the assembly is initially as illustrated in figure 1 which is prior to use.

At this stage, there is no vacuum in the assembly, and the steel puncture needle 14 is protected by cap 11.

To apply a vacuum to the assembly (or to cock the assembly for use), the cap 11 and barrel 10 are pulled away from each other. In practice, barrel 10 is usually held by a person and cap 11 is pulled out of barrel 10. Cap 11 is attached to collar 12 as described above, and therefore as cap 11 is pulled out of barrel 10, collar 11 is pulled with it. Trigger means 17 is attached to collar 12 and functions to releasably lock plunger 13 to collar 12. This means that as cap 11 is pulled out of the barrel 10, it will also pull out collar 12, trigger means 17, and plunger 13. As plunger 13 is pulled out of the barrel, rubber bung 34 begins to move along the barrel and as the rubber bung is in sealing engagement with the inside wall of barrel 10, a vacuum will be created between the rubber bung and end wall 18. The vacuum will bias plunger 13 back towards the retracted position.

Cap 11 is continued to be pulled out of barrel 10 until such time as trigger means 17 emerges from the open front 19 of the barrel. As the trigger 17 is slightly biased due to the leg members 42, 43 being partially spread by wedge block 47, as soon as trigger means 17 is free from the confines of the barrel, it will move in the direction of arrow 54 illustrated in figure 9 by a small distance ,typically about 1 mm. This is enough to now have the trigger means extending over or at least against the open end 19 of barrel 10. Thus, cap 11 cannot now be pushed back into the barrel because of the extending trigger means. This cocked position is illustrated in figure 4.

To prevent cap 11 from being pulled to far, the collar retaining ring 20 which is adjacent the open front end 19 of barrel 10 locks against a shoulder 57 which is on collar 12.

Once cap 11 has been pulled out of the barrel as illustrated in figure 4, its leg members 27, 28 can be squeezed towards each other to free barbs 29 from the cutouts 30 on collar 12 (There is of course a second barb on the other leg 28 which can be freed from its associated cutout 31 on collar 12). This allows cap 11 to be pulled away from the remainder of the needle assembly. This is illustrated in figure 5. At this point, the cannula is fully exposed.

The puncture needle 14 can then be inserted into a vein, and thereafter the cannula can be pushed forwardly in the direction of arrow 59 illustrated in figure 6 to insert the cannula needle 15 into the vein. A small projection extends from cannula base 16 which facilitates pushing forward of the cannula.

Once the puncture needle 14 enters into a vein, blood will flow through the lo puncture needle 14 and into hollow chamber 36 of the plunger 13. This can be viewed, and at this stage the puncture needle 14 can be retracted. This is achieved by depressing trigger means 17 which will force the leg members 42, 43 to ride over wedge block 47 which will force the leg members progressively further apart. At some point, the leg members are forced apart sufficiently such that the thickened portions 45, 46 become freed from the cutouts 50,51 in plunger body 33. As soon as this occurs, the vacuum created in the barrel will suck back or push back plunger 13 towards the bottom or rear end 18 of the barrel. As plunger 13 is connected to puncture needle 14, this will also shoot the puncture needle back into the barrel. This 2 0 is illustrated in figure 7.

Figure 8 illustrates the final position where the puncture needle 14 and plunger 13 have been sucked back into the barrel and the barrel now protects all parts of the needle. Once trigger means 17 is released, it will be biased back into its cocked position.

The assembly provides a reliable means to protect against a sharps hazard or a bio-hazard by accidental attachment of the contaminated needle. The needle is retracted using vacuum, but the vacuum is created just prior to use, and there is no vacuum in the assembly before the assembly is cocked to create the vacuum.

It should be appreciated that various other changes and modifications may be made to the invention described without departing from the spirit and scope of the invention as claimed.

Claims (3)

1. A retractable needle assembly where the needle is retracted by a vacuum, the assembly comprising a needle which is moveable between a retracted position and an extended position, and vacuum creation means which is operatively associated with the needle such that movement of the needle from the retracted position to the extended position results in creation of the vacuum.

2. The assembly of claim 1 comprising a catheter and which uses a vacuum to retract the needle, the assembly comprising: a. a tubular barrel which is closed at a rear end and open at a front end, b. a removable cap which is slidable in the barrel from a retracted position where the cap is substantially within the barrel to an extended position where the cap can be removed, c. a collar which is slidable within the barrel, d. a plunger in the barrel and which is moveable along the barrel between a retracted position where the plunger is adjacent the closed rear end of the barrel, and a vacuum creating extended position where the plunger is at a position spaced from the rear end, and a vacuum is created between the plunger and the rear end which biases the plunger back towards the retracted position, e. a puncture needle operatively connected to the plunger, f. a cannula having cannula needle which extends over the needle, and a cannula base to which cannula needle is attached, g. engagement means to releasably connect the cap to the collar, and, h. trigger means which operatively connects the plunger to the collar, the trigger means extending from the barrel when the cap is in the extended position, and in this position able to be operated to release the plunger from the collar causing the plunger to be biased by the vacuum back to its retracted position which causes the attached puncture needle to be retracted into the barrel.

3. The assembly of claim 1 or claim 2 substantially as hereinbefore 16 described with reference to the drawings. DATED this 1 st day of February 2001 OCCUPATIONAL MEDICAL INNOVATIONS LTD (ACN 091 192 871) By their Patent Attorneys CULLEN CO